1. Field of the Invention
The present invention relates to a charging apparatus, and in particular to a charging apparatus that provides electric power to external devices using electromagnetic induction.
2. Description of the Related Art
Contactless charging apparatuses that use electromagnetic induction have been known. Such charging apparatuses utilize the principle of electromagnetic induction in which a magnetic field generated by an electric current flowing in a primary coil provided in a charging apparatus causes a voltage to be generated across both ends of a secondary coil provided in an external device. In these charging apparatuses, when a foreign object such as a piece of metal (for example, a coin) is placed within the magnetic field generated by the primary coil, an eddy-current flowing in the piece of metal may cause heat to be generated due to the internal resistance of the piece of metal.
To address such a problem, a charging apparatus has been proposed (for example, US 2007/0069687) that does not activate a charging circuit of the charging apparatus until it detects that a chargeable device has been placed on the charging apparatus, by means of authentication using a contactless IC card.
However, the charging apparatus described above does not take into consideration a case in which a plurality of devices are being charged in parallel. Hence, when a chargeable device and a non-chargeable device are placed on the charging apparatus at the same time, for example, there remains a problem in which a charging operation may possibly be started despite the presence of a non-chargeable device on the charging apparatus, causing the non-chargeable device to generate heat.